1. I CAN FIND UNKNOWN ANGLE MEASURES BY WRITING AND SOLVING EQUATIONS. 6.1 Angle Measures

2. Angle A figure formed by two rays with a common endpoint or vertex. The symbol ∠ means angle. When an m is placed in front it means “the measure of the angle”

3. Angle Measure Sums If the sum of two angle measures is 90°, the angles are complementary. If the sum of two angle measures is 180°, the angles are supplementary.

4. Adjacent Angles Share a vertex and a side but have no interior points in common. Ex: Angles 1 and 2 are adjacent.

5. Finding Supplements and Complements The Leaning Tower of Pisa Find each angle measure We know a straight line measures 180° 3x – 35 and 2x must be supplements So 3x – 35 + 2x = 180 x = 43 Substitute and the measures are 3(43) – 35 and 2(43) 94° and 86°

6. You try! Complementary means the sum is 90° m ∠ A + m ∠ B = 90 and m ∠ A = 5(m ∠ B) 5(m ∠ B) + m ∠ B = 90 6(m ∠ B) = 90 m ∠ B = 15°

7. 6.1 Continued

8. Vertical Angles Formed by two intersecting lines and are opposite each other. Vertical angles have equal measure. Angles with equal measure are congruent angles. EX: Angles 1 and 2 are vertical angles

9. Practice Find m ∠ 2, m ∠ 3, and m ∠ 4 if we know that m ∠ 1 = 25.7° m ∠ 2 = 154.3° m ∠ 3 = 25.7° m ∠ 4 = 154.3°

10. Try this!

11. Assignment All P.218 #7-19